Licensing explanation

2010-04-19

I’m not a lawyer — I don’t even play one on TV — but here’s
a summary of how I managed to confuse myself, and others
who read the small print, with XML::Writer.

David Megginson’s original license for XML::Writer is brief:
“No warranty. Commercial and non-commercial use freely permitted.”
It’s been there at the head of the code since the
first release in 1999. It allows any use,
without even the obligation to redistribute under the same
license.

Placing something you’ve created in the public domain is
not generally possible, so a liberal licence is the
best available option.

(It also carried the
“under the same terms as Perl itself” license in its README. Under the
circumstances, this was a more restrictive
license than the main one: a fairly redundant form
of dual licensing.)

For the next nine years, and three maintainers, it included
the same text. However, it’s not
OSI-approved, nor is it likely to be:
licence-tracking systems
(e.g., META.yaml’s license field)
won’t know about it. So, at the end of 2008 I switched to the
MIT licence. This
permits any use with the requirement that the same
notice is included in any copies.

When I got a question a year later about commercial use and
some licence inconsistencies, I was concerned.
Amongst my mistakes, I didn’t include the
MIT notice in the source text, left in the ‘same terms as Perl’
remark and declared it as GPL on its source hosting site.
Not ideal.

The first step was to create a clear history,
hence the migration to Git.
I then confirmed with all contributors that they
placed their work under
the original license along with its ‘anything permitted’
interpretation.

Thanks; almost everyone immediately confirmed.
(Update: as of 2010-07, all contributors have
given permission.)

As part of the resolution, I decided to respect David’s
choice of licence and to
remove the ‘same terms as Perl’ notice to avoid confusion. This
allows anyone receiving the code to combine it with any
license they wish, including simply putting it under the
MIT license themselves.

So, there’s the current state: do anything, with
a public history if you need an audit. I learned a lot more
about licensing and hopefully managed to resolve any
inconvenience that I caused.